In 2012, he was an adviser to the national security transition team for the Mitt Romney presidential campaign.[2]

Mitchell has co-authored two books, The Unquiet Frontier: Vulnerable Allies, Rising Rivals and the Crisis of American Power with Jakub J. Grygiel and The Godfather Doctrine: A Foreign Policy Parable with John Hulsman. He serves on the advisory councils of the Richard G. Lugar Institute for Diplomacy and Congress, the Slovak Atlantic Commission, the Prague Center for Transatlantic Relations, the Atlantic Initiative, and the Alexander Hamilton Society.[2]